Unequal Line (uL) Calibrator Input Mismatch Correction for TRuL calibration method

An input mismatch correction method for TRuL calibration method is proposed. The input mismatched uL calibrator is transformed into an equivalent matched uL calibrator for the afterward TRuL calibration method. The eigenvalues of this equivalent uL calibrator are distinct even when line length is equal to 0deg or 180deg. The measured scattering matrix of a branch line coupler on FR4 substrate using proposed correction method shows good agreement with simulation and the errors caused by 0deg or 180deg line length is reduced.